1. Field of the Invention
The present invention relates to a projection display device for enlarging and projecting an image on a display element on a projection plane, and is particularly preferable for being used as a projection display device in which an image on the display element is formed as an intermediate image between a projection lens section and a reflection mirror, and this intermediate image is enlarged and projected by a reflection plane.
2. Description of the Related Art
Projection display devices (hereafter, referred to as “projectors”) for enlarging and projecting an image on a display element (liquid crystal panel, or the like) on a projection plane (screen, or the like) have been commercialized and widely used. In the projectors of this sort, it is desirable to reduce a distance between the screen and the projector body.
To attain this, an arrangement for oblique projection may be used in which a projection optical system is wide-angled, and at the same time, a direction of projection light traveling is oblique to an optical axis of the projection optical system. For example, when a wide-angle lens with a large view angle is used as the projection optical system, and a display element and a screen are shifted in opposite directions to each other with regard to the optical axis of the projection optical system, a projection distance is shortened, and at the same time, oblique projection without distortion can be achieved. However, with the arrangement as mentioned, a wider-angle lens with a larger view angle is necessary, and therefore, increased costs due to a large-sized lens and a large-sized projector body pose a problem.
On the other hand, for realization of the reduced projection distance, such an arrangement is also considered that a projection lens section and a mirror are used as a projection optical system, an image on a display element is formed as an intermediate image between the projection lens section and the mirror, and the intermediate image is then enlarged and projected by the mirror.
With the projectors of this type, in general, focus adjustment and zoom adjustment are performed in a projection lens unit. For example, an operation section operated by a user is provided, operation at the operation section causes displacement of a lens position in the projection lens unit in a direction of an optical axis, and then, focus adjustment and zoom adjustment are carried out.
However, with a projector of the latter in which light from the projection lens unit is reflected by the reflection mirror, the light reflected to the projection lens unit side by the reflection mirror passes in a vicinity of the projector body. For this reason, an operation section itself may hinder the optical path, or fingers of the user manipulating the operation section may hinder the optical path depending on an arrangement of the operation section for focus and zoom adjustments, and there is a possibility that a shadow is cast on a projected image.